With the development of the communication technology, services provided by a mobile communication system are being gradually developed into packet data transmission and/or reception services, multimedia broadcasting services, and the like, as well as voice communication services.
In the third generation services, such as WCDMA, high capacity data as well as voice can be transmitted and received at a high transmission rate, and furthermore, the standardization work is actively carried out, such as long-term evolution network (LTE), IEEE 802.16m, and the like, in order to make an evolved network having a wider bandwidth, considering a rapid increase of data traffic in the future.
In particular, IEEE 802.16m, for which its standardization work is actively carried out, has set a goal to develop a standard specification satisfying the requirement of an IMT-Advanced system while maintaining compatibility with 802.16-based terminals and base station equipment. In the IMT-Advanced system, above all, more than 40 MHz of broadband communication service support is required, and in IEEE 802.16m, broadband communication support is also essential to satisfy the requirement of the IMT-Advanced system. However, it is in fact difficult to define a standard for all bandwidths, and as a result, a communication system using a multi-carrier approach that supports broadband using a plurality of carriers is under discussion. In the multi-carrier system, discussed under IEEE 802.16m, it is possible to transmit and/or receive data between a terminal and a base station by accessing to each other through at least two and more frequency assignments (FAs) at the same time, and therefore, it has an advantage that high-capacity, high-speed data transmission and reception is possible compared to the existing single-carrier approaches. Also, it has a feature that communication is possible using a broader bandwidth from the standpoint of a mobile station (MS) depending on circumstances, and more users can be accommodated from the standpoint of a base station (BS).
In a system using a multi-carrier approach, as described above, a terminal generally transmits and/or receives data to and/or from a serving base station using all available carriers to obtain the maximum data transmission efficiency. In those circumstances, when such a circumstance occurs that a terminal should perform handover, it may cause a problem that a link connection with the serving base station should be terminated to perform handover since there exists no carrier for performing a handover procedure to a target base station while maintaining the link connection with the serving base station. Accordingly, the termination of the link connection with the serving base station for performing handover procedure with the target base station causes a handover delay time. Also it causes a problem that the quality of service (QoS), obtained by the terminal using a multi-carrier, cannot be continuously guaranteed.